As the type of broadcasting changes from analog to digital, there is an increasing demand for transmitting System Information (SI) and Program Guide (PG) of a broadcast program to a receiver through a broadcasting channel in a digital broadcast emitting system.
For this, the Advanced Television Systems Committee (ATSC) defines the Program and System Information Protocol (PSIP), a standard specification for transmitting system information and program guide of a broadcast program in a form of transport stream (TS) based on the Moving Picture Experts Group (MPEG)-2 System specifications.
The ATSC names a broadcast emitting device transmitting the system information and program guide of a broadcast program in the form of transport stream based on the PSIP as a PSIP server or a PSIP generator. The PSIP information is primarily authored by a program manager of a broadcasting station through a program management system and transmitted to the PSIP server. The primarily authored PSIP information can be updated, deleted or have additional information upon a change in a broadcasting schedule before final broadcasting.
The change in the broadcasting schedule occurs in a broadcast emission controlling device such as a traffic system, an automation system, and an MPEG controller. The broadcast emission controlling device should inform the PSIP server of changed program guide so that the PSIP server can update the PSIP information.
However, interface independently defined by each operator to exchange changed broadcast program guide cannot secure inter-operability between digital broadcast emitting systems developed by various companies, i.e., broadcast emission controlling devices, and the PSIP server. This calls for more efforts and costs for realizing an interface between broadcasting devices on the parts of an operator of a digital broadcast emitting system and hardware developers when a broadcast emitting system is built up.
In order to resolve the problems, the ATSC defines a metadata structure and a metadata transmitting method in an ATSC A/76 Standard called Programming Metadata Communication Protocol (PMCP) to exchange standardized PSIP information between constitutional devices of the digital broadcast emitting system.
FIG. 1 is a structure of metadata defined in the PMCP specification. As shown in FIG. 1, a PmcpMessage metadata 100 includes message state metadata 110, i.e., PmcpReply metadata; transport stream (TS) metadata 120, i.e., TransportStream metadata; channel metadata 130; show metadata 140; PSIP event metadata 150, i.e., PsipEvent metadata; time parameters metadata 160, i.e., TimeParameters metadata; rating metadata 170, i.e., Ratings metadata; and user definition metadata 180, i.e., PrivatePmcpInformation metadata. The PmcpReply metadata 110 describes validity and process status of transport stream. The TransportStream metadata 120 described information of transport stream. The Channel metadata 130 describes virtual channel information and channel tuning information. The Show metadata 140 describes a play list of a show used for broadcast program guide. The PsipEvent metadata 150 describes the broadcast program guide. The TimeParameters metadata 160 describes system time information. The Ratings metadata 170 describes a rating of a broadcast program. The PrivatePmcpInformation metadata 180 describes PMCP user definition information of a system level.
The PmcpMessage metadata 100 describes information needed for the PSIP server to generate PSIP/program specific information (PSI) in a form of transport stream. That is, the PMCP specification only considers the providing of metadata needed for the broadcast emitting system to transmit the PSIP and PSI, which are system information and program guide of an audio/video broadcast program, i.e., a broadcast program formed of audio, video or both audio and video, in a digital broadcasting environment.
However, the broadcasting environment takes its own course from a conventional digital broadcasting environment where viewers simply watch audio/video only to a digital data broadcasting environment where the viewers can receiver diverse services by receiving broadcast programs along with data.
In order to provide data broadcasting, a broadcast emitting device for encapsulating data broadcasting contents based on a data broadcasting specification and outputting the encapsulated data broadcasting contents in the form of MPEG-2 transport stream should be added to a conventional digital broadcast emitting system. The broadcast emitting device is generally called a data server or a data stream generator.
A data server should be able to receive program guide and encapsulation information to generate data stream just as a PSIP server for a digital service and change the program guide and encapsulation information in a broadcast emitting controlling device such as a traffic system, an automation system, an MPEG controller.
However, since the conventional PMCP does not describe encapsulation information and program guide for data broadcasting, it is not appropriate as an interface of a broadcast emitting system with secure inter-operability for data broadcast emission. Therefore, a technological solution which is added to a broadcast emitting system and securing the inter-operability between broadcasting devices is required to transmit digital data broadcasting.